The present invention relates to an insulation material for use on subsea oil and gas production equipment.
When subsea oil and gas wells are located at depths of 5,000 feet or more, the pipelines and wellhead equipment are exposed to seawater which is just a few degrees above freezing. This same temperature can exist in shallow water at extreme latitudes, such as in the North Sea. During a temporary well shutdown, hot produced hydrocarbon fluids within the production equipment become stagnant and are cooled by the surrounding seawater. If the stagnant fluids approach the seawater temperature, hydrates can form in the equipment and block the flow of the fluid.
Thermal insulation is sometimes installed around hydrocarbon production equipment components such as subsea pipelines and wellheads to slow the cooling process and delay hydrate formation until flow can be restored. To perform successfully in this environment, a thermal insulation material must have a low thermal conductivity, exhibit acceptable mechanical properties such as flexibility and impact resistance, and be economical to install.
In many subsea wells, especially those in deep water, the insulation requirements are further complicated by the extreme temperatures of the hydrocarbon fluids exiting the well. In some cases the temperature of the exiting fluids may reach 300° F. or higher, and the fluids will consequently heat both the surrounding equipment and the insulation. Therefore, any insulation material which is used on such wells must be able to withstand these extreme temperatures without detriment to its thermal or mechanical properties.
Although insulation materials exist which can withstand these relatively high temperatures, they are inherently brittle. Therefore, these materials are unable to meet the flexibility and impact resistance requirements of many applications. Furthermore, because of their brittle nature and exothermic curing properties, these materials are difficult and expensive to install and repair. Examples of these types of prior art insulation materials include syntactic phenolic foams and high temperature epoxy resins.
Conversely, existing insulation materials which exhibit acceptable flexibility and impact resistance characteristics are unable to withstand the relatively high flow temperatures present in may deep water wells. Examples of these types of prior art materials include amine cured epoxies, urethanes and polypropylenes.